[PATCH] SRCU: report out-of-memory errors

Currently the init_srcu_struct() routine has no way to report out-of-memory
errors.  This patch (as761) makes it return -ENOMEM when the per-cpu data
allocation fails.

The patch also makes srcu_init_notifier_head() report a BUG if a notifier
head can't be initialized.  Perhaps it should return -ENOMEM instead, but
in the most likely cases where this might occur I don't think any recovery
is possible.  Notifier chains generally are not created dynamically.

[akpm@osdl.org: avoid statement-with-side-effect in macro]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/sys.c b/kernel/sys.c
index fd5c710..98489d8 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -517,7 +517,8 @@
 void srcu_init_notifier_head(struct srcu_notifier_head *nh)
 {
 	mutex_init(&nh->mutex);
-	init_srcu_struct(&nh->srcu);
+	if (init_srcu_struct(&nh->srcu) < 0)
+		BUG();
 	nh->head = NULL;
 }